This application is a continuation of International PCT/EP03/02347 filed on Mar. 7, 2003 and which claims priority from patent application Ser. No. 02/03272 filed in France on Mar. 13, 2002.
The present invention relates to the technical sector of vehicles known as construction vehicles, such as loaders, dumpers, lorries and similar vehicles which are suitable for loading, unloading and/or transporting materials such as, in particular, ores or similar materials, and which for the sake of simplicity are called “vehicles” hereinbelow.
The technical problem arising is to determine quickly and accurately on site, that is to say at the building site, the optimum values for the internal pressure of tires which should be set up for the front wheels (AV) and back wheels (AR) of these vehicles as a function of a very large number of parameters relating to the vehicle, the way it is used, the terrain on which it is to travel, the parameters of the available tires, the characteristics of the load and similar factors well known to those skilled in the art.
Basic methods are currently known, consisting essentially in making a visual assessment of the behavior of the vehicle under load and deducing the pressures which seem most appropriate therefrom, by manual and empirical calculation. This is highly imprecise.
It is known that the risk associated with such vehicles under load, in particular front-end loaders, is that they may tip forwards under the effect of an excessively large load in the bucket and inappropriate parameters in selecting the tires and pressure.
On the ground, those skilled in the art will of course tend to recommend smaller loads in order to avoid this risk, and hence of course a markedly lower output from the vehicle, but also of course inflation pressures for tires which are suitable for the maximum load (tipping) and of course a greater sensitivity to cuts in the tires and hence lower output.
It is also known that too low a pressure must not be advocated, but that too high a pressure must not be advocated either, since in this latter case there then arises a risk of the tire being cut or torn on certain terrains.
Other factors to take into account are the stability of the vehicle, which those skilled in the art know they can improve by increasing the operating pressure, but those skilled in the art also know that this has a negative effect on the vehicle's flotation, that is to say its capacity to travel on loose or soft terrain or even muddy terrain.
It will therefore be appreciated that the parameters are not merely extremely numerous but in some cases incompatible. There are moreover numerous types and makes of vehicles, tires available, and so on, which make solving the problem even more complicated.
There is thus a recognized and major need for a method and a system which are simple and accurate and ensure that operations are safe and optimized.